The present invention relates to an elastomer composition. More particularly, it relates to an elastomer composition excellent in appearance, flexibility (feel), mechanical strength and melt processability.
There have already been known thermoplastic elastomer compositions obtained by so-called dynamic crosslinking. Namely crosslinking a rubber-like polymer such as a radical crosslinkable olefin elastomer and an olefin resin having no radical crosslinkability, such as PP, under melt-kneading them in an extruder in the presence of a radical initiator. These compositions are widely employed for uses such as automobile parts.
As these olefin elastomers, there have been known ethylene-propylene-diene rubbers (EPDM) or olefin elastomers produced using metallocene catalysts (JP-A-60-231747, JP-A-8-120127 and JP-A-9-137001). However, these compositions disclosed in the patent publications are not necessarily sufficient in appearance, flexibility (feel), mechanical strength and melt processability, and better elastomer compositions have been demanded.
Under the circumstances, the object of the present invention is to provide an elastomer composition free from the above-mentioned problems, namely, excellent in appearance, flexibility (feel), mechanical strength and melt processability.
As a result of intensive research conducted by the inventors for providing elastomer compositions excellent in appearance, flexibility (feel), mechanical strength and melt processability, surprisingly, it has been found that they are markedly improved in appearance, mechanical strength and melt processability with maintaining flexibility by adding a polypropylene resin having a specific structure to rubber-like polymers. Thus, the present invention has been accomplished.
That is, the present invention provides an elastomer composition obtained by crosslinking 1-99 parts by weight of a crosslinkable rubber-like polymer (A) and 1-99 parts by weight of a polypropylene resin (B) [the total amount of (A) and (B) being 100 parts by weight], wherein (B) is a crosslinking type polypropylene resin and has a flexural modulus of 100-10000 kgf/cm2 measured in accordance with JIS K6758 and has a peak of melting point in the range of 100-150xc2x0 C. in differential scanning calorimetry (DSC), the calorie in the peak of melting point being in the range of 10-600 J/g, and particularly provides the above composition in which (A) has a crosslinking degree of 1-95% and a swelling degree of 3-100.